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|
package regex
import (
"fmt"
"regexp"
"strings"
"github.com/mimecast/dtail/internal/io/logger"
)
// Regex for filtering lines.
type Regex struct {
// The original regex string
regexStr string
// The Golang regexp object
re *regexp.Regexp
// For now only use the first flag at flags[0], but in the future we can
// set and use multiple flags.
flags []Flag
initialized bool
}
func (r Regex) String() string {
return fmt.Sprintf("Regex(regexStr:%s,flags:%s,initialized:%t,re==nil:%t)",
r.regexStr, r.flags, r.initialized, r.re == nil)
}
// NewNoop is a noop regex (doing nothing).
func NewNoop() Regex {
return Regex{
flags: []Flag{Noop},
initialized: true,
}
}
// New returns a new regex object.
func New(regexStr string, flag Flag) (Regex, error) {
if regexStr == "" || regexStr == "." || regexStr == ".*" {
return NewNoop(), nil
}
return new(regexStr, []Flag{flag})
}
func new(regexStr string, flags []Flag) (Regex, error) {
if len(flags) == 0 {
flags = append(flags, Default)
}
r := Regex{
regexStr: regexStr,
flags: flags,
}
re, err := regexp.Compile(regexStr)
if err != nil {
return r, err
}
r.re = re
r.initialized = true
return r, nil
}
// Match a byte string.
func (r Regex) Match(bytes []byte) bool {
switch r.flags[0] {
case Default:
return r.re.Match(bytes)
case Invert:
return !r.re.Match(bytes)
case Noop:
return true
default:
return false
}
}
// MatchString matches a string.
func (r Regex) MatchString(str string) bool {
switch r.flags[0] {
case Default:
return r.re.MatchString(str)
case Invert:
return !r.re.MatchString(str)
case Noop:
return true
default:
return false
}
}
// Serialize the regex.
func (r Regex) Serialize() string {
var flags []string
for _, flag := range r.flags {
flags = append(flags, flag.String())
}
if !r.initialized {
logger.FatalExit("Unable to serialize regex as not initialized properly", r)
}
return fmt.Sprintf("regex:%s %s", strings.Join(flags, ","), r.regexStr)
}
// Deserialize the regex.
func Deserialize(str string) (Regex, error) {
// Get regex string
s := strings.SplitN(str, " ", 2)
if len(s) < 2 {
logger.Debug("Using noop regex", str)
return NewNoop(), nil
}
flagsStr := s[0]
regexStr := s[1]
if !strings.HasPrefix(flagsStr, "regex") {
return Regex{}, fmt.Errorf("unable to deserialize regex '%s': should start with string 'regex'", str)
}
// Parse regex flags, e.g. "regex:flag1,flag2,flag3..."
var flags []Flag
if strings.Contains(flagsStr, ":") {
s := strings.SplitN(flagsStr, ":", 2)
for _, flagStr := range strings.Split(s[1], ",") {
flag, err := NewFlag(flagStr)
if err != nil {
logger.Error("ignoring flag", err)
continue
}
logger.Debug("Adding regex flag", flag)
flags = append(flags, flag)
}
}
return new(regexStr, flags)
}
|
